In the field of manufacturing integrated circuit (IC) and semiconductor device, the technique of forming a layer on a wafer is very important. The layer can be used as a gate oxide layer of metal-oxide-semiconductor (MOS), a field oxide layer for trench-isolating other devices, a mask for ion implantation and diffusion, a capping layer for preventing dopants from diffusing out, or a passivation layer for protecting a device from being scratched by dirt. There are many methods for growing a layer on the wafer, e.g. thermal oxidation, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and electron cyclotron resonance chemical vapor deposition (ECRCVD). Both of the gate oxide and field oxide have to be made by the thermal oxidation because only the thermal oxidation can provide a oxide layer with a low interface trap density. However, technologically speaking, every method has its own limitation in usage. For the thermal oxidation, the required high temperature (700.about.1200.degree. C.) will easily deform the chip and destroy the structure (because of the redistribution of the dopants). The main drawbacks of the CVD method are the expensive equipment and the requirement of precisely-controlled temperature for forming a layer. As for other methods, they need not only the expensive equipment but a growing temperature over 300.degree. C. and are also more complex.
The liquid phase deposition (LPD) method is a new method for growing oxide layers. The growing temperature of this method is low (about 40.degree. C.) and the equipment is relatively cheap. Therefore, the LPD method is very useful for manufacturing the integrated circuit and the semiconductor device. However, no specific technique or process is needed for producing a great number of wafers, each of which has a LPD layer thereon. Like other methods, the LPD method has a problem that the layer will grow on both surfaces of a wafer. The process of etching the LPD layer on the back of a wafer is necessary after the layer is grown. If there is an apparatus and a method that can control the growth of the LPD layer only on one surface of a wafer, the cost and time of growing LPD layer on the back will be saved, and the process of etching the LPD layer on the back, of course, will be needless.
Therefore, the present invention provides a method and an apparatus for growing a layer on one surface of a wafer by the LPD method. The apparatus of the present invention is low-cost and the method of the present invention is relatively simple and effective. The present invention makes the LPD method more useful.